This invention relates to a method for trimming a metal interconnection layer of a semiconductor device.
A technique is known in the art which trims an interconnection layer so as to obtain, for example, highly accurate resistors. The trimming process has been carried out as follows: First, an insulating film is formed on the surface of a semiconductor substrate and a semiconductor or a metal interconnection layer is formed on the insulating film. A passivation film is formed on the interconnection layer. Then, a high energy laser beam selectively illuminates predetermined portions of the interconnection layer to permit the interconnection layer to be locally heated to about 650.degree. C. This process causes the interconnection layer to be melted, trimming or partially eliminating the interconnection layer.
In the above-mentioned trimming technique such a high energy laser beam is directed onto the interconnection layer and, therefore, there is a possibility that a crack will occur in a passivation film and that damage will take place at the underlying insulating film or semiconductor substrate. With a resin-sealing type semiconductor device in particular, the interconnection layer is liable to be attacked, prominently lowering the reliability with which the semiconductor device operates. Furthermore, where the underlying insulating film and semiconductor substrate are damaged, a short-circuiting occurs between the interconnection layer and the semiconductor substrate, resulting in lowered reliablity.